Method for producing a sensing element for a thermal flow meter, sensing element and flow meter

Abstract

The present disclosure relates to a method for producing a probe of a thermal flow meter for measuring the mass flow rate of a medium in a measuring tube, the method having the following steps: introducing a probe core in the form of a material to be melted into a first probe casing, the first probe casing having an open first end and a closed second end facing away from the first end; melting the probe core; quenching the probe core to a temperature below the solidification temperature; attaching a thermoelement to a contact surface of the solidified probe core. The invention also relates to a probe obtained according to the production method and to a flow meter including the probes according to the present disclosure.

The invention claimed is: 
     
       1. A method for producing a probe of a thermal flow meter for measuring the mass flow rate of a medium in a measuring tube, the method comprising:
 introducing a probe core in the form of a material to be melted into a first probe casing, wherein the first probe casing includes an open first end and a closed second end opposite the first end; 
 melting the probe core; 
 cooling the probe core to a temperature lower than a solidification temperature of the material to be melted; 
 after cooling the probe core, exposing a region of the probe core by removal of at least a portion of a wall of the first probe casing; and 
 attaching a thermoelement to a contact surface of the solidified probe core. 
 
     
     
       2. The method of  claim 1 , wherein the contact surface is prepared by machining the solidified probe core to form an area configured for attaching the thermoelement. 
     
     
       3. The method of  claim 1 , further comprising, after exposing the region, attaching a open third end of a second probe casing to the first end of the first probe casing in a leak-tight manner, wherein the second probe casing further includes an open fourth end opposite the open third end, wherein the second probe casing surrounds the region. 
     
     
       4. The method of  claim 3 , wherein the region is machined in a subregion such that the subregion of the probe core is separated from all surfaces of the first probe casing and/or the second probe casing, wherein the subregion includes all cross-sections of the probe core that intersect or touch the contact surface. 
     
     
       5. The method of  claim 1 , wherein the thermoelement is attached to the contact surface of the probe core using a solder or sinter layer. 
     
     
       6. The method of  claim 1 , wherein cooling the probe core includes quenching the probe core to a temperature lower than the solidification temperature. 
     
     
       7. The method of  claim 1 , wherein the thermoelement is configured to increase and/or detect a temperature of the probe core.